Why do they only seem to drink water at chess tournaments?

BonTheCat

Carlsen stopped drinking orange juice because it gave him sugar highs. Just like any fruit juice, OJ is high in sugar (or more specifically fructose). No one would think of consuming 15 oranges or 30 apples during the course of a game. But 1 litre of fruit juice or, even worse, coca-cola or other fizzy drinks, many seem to do without as much as batting an eyelid. Personally I prefer water and coffee.

As for the reason we go to the toilet/bathroom so often during the game, isn't that simply caused by the nervous tension? When I was in my teens, I used to get headaches after the game, due to the high tension.